Grey's Anatomy (2005): Don't Deceive Me (Please Don't Go)

Derek breaks ground on his Alzheimer's clinical trial and Meredith can't help but feel left out; Bailey's attempt to take the hospital into the age of new media with live tweets from the OR does not go over well with the Chief; and Callie, Mark and Arizona must learn to navigate through the pregnancy together, which starts off with Callie driving her new obstetrician crazy.